1. Field
The present invention relates to an outboard motor, and more specifically to an outboard motor having a system for distributing lubricant in a lower casing of the outboard motor.
2. Description of Related Art
In outboard motors designed for small watercrafts or the like, the driving force from an engine is transmitted from a drive shaft to a propeller shaft via a bevel gear mechanism to produce propulsion force.
In this type of outboard motor, a lower casing for holding the drive shaft, bevel gear mechanism and propeller shaft therein is subjected to a reaction force directly from water when the outboard motor is driven in water. Thus, the lateral width of the lower casing is typically kept very small. Accordingly, the bevel gear mechanism and the other parts described above are disposed in a limited space within the lower casing.
To prolong the life of meshing parts of the bevel gear mechanism and bearings of the propeller shaft, lubricant is circulated in the lower casing to cool and lubricate such parts.
According to Japan Patent No. 2863601, for example, the propeller shaft has an oil passage formed therein. The oil passage extends axially along the propeller shaft from a front end of a bevel gear mechanism attachment part of the propeller shaft to a rear end thereof, and further extends radially of the propeller shaft and is open upward. Lubricant can thus circulate through the oil passage between the front end and the rear end of the bevel gear mechanism attachment part.
However, in a conventional outboard motor in which lubricant circulates between the front end and the rear end of the bevel gear mechanism attachment part of the propeller shaft, part of the lubricant lubricating a bearing at a rear end of the propeller shaft may stagnate, resulting in decreased bearing life.